Retraction

I spent some time tweaking my retraction settings using a small columns test print.
I got it to the point where I didn't see any stringing between the columns.

Length 3mm
Speed 40mm/s
Retract on Layer change



I still see a lot of stringing though on other prints, but only on what appears to be be layer changes (when the print head has to move across the object). You can see there's no stringing inside each of the cutouts in the print, it's all inside the 4 walls of the box.



Is Slicer perhaps ignoring my "Retract on Layer change" or is there more to retraction than how I set it?

Any suggestions would be appreciated.
Thanks.

What I noticed in my own prints is that my printer needs more retract after drawing a circle and less when it is doing a layer change.

The speed of your layer change also influences the amount of oozing and lastly, there should be an option for your hotend not to cross external boundaries on layer change so the oozetrail stays inside the print.